1. Field of the Invention
The present invention relates to a polyarylene sulfide composition and, more particularly, to a polyarylene sulfide composition having improved mechanical properties such as impact resistance, bending strength and so on, while maintaining heat resistance and fire retardancy inherent in the polyarylene sulfide of the composition, which can be appropriately utilized in the mechanical, electrical and electronic fields.
2. Description of Related Art
Polyarylene sulfides (PAS), such as polyphenylene sulfide (homo-PPS), having excellent physical properties, such as heat resistance, fire retardancy, high rigidity and so on, have been extensively used in many fields as engineering plastics.
However, the polyarylene sulfide resins are so insufficient in impact resistance that a fibrous reinforcing material is generally blended in order to improve their impact strength, however, their impact strength cannot be said to reach a sufficient level for some uses.
Therefore, in order to further improve the impact strength of the polyarylene sulfide resins, it is known to blend an elastomer with the polyarylene sulfide resins. The resulting resin compositions are provided with improved impact strength yet their mechanical properties such as, for example, bending strength or heat resistance including heat distortion temperature may be reduced. Further, their solvent resistance may be reduced.
Furthermore, a blend of polyphenylene sulfide (homo-PPS) with an epoxy resin and glass fibers cannot yet be said to be sufficient from a standpoint of an improvement in impact strength.
Therefore, demands have been made to improve mechanical strength, particularly impact strength, of the polyarylene sulfide resin compositions of such a type without causing a substantial decrease in heat resistance.
On the other hand, the polyamide resins have the problems with water absorbency, although they have excellent characteristics, such as heat resistance, high rigidity and so on.
Attempts have so far been made to improve the properties inherent in both the polyarylene sulfide resin and the polyamide by making them a polymer alloy. Japanese Patent Examined Publication (kokoku) No. 1,422/1984 (Unexamined Publication (kokai) No. 69,255/1978) discloses a simple blend of a polyarylene sulfide and a polyamide. This resin composition, however, provides the problem that compatibility between the two resins is so insufficient that it cannot impart a sufficient improvement in its physical properties.
Japanese Patent Unexamined Publication (kokai) No. 155,462/1984 discloses a resin composition in which a polyarylene sulfide is blended with an epoxy resin. This resin composition suffers from the problem that compatibility between the two resins is not yet sufficient because there is no site on the polyarylene sulfide on which it can react with the epoxy resin although the epoxy resin is added for the purpose of improving the compatibility of the polyarylene sulfide.
Further, Japanese Patent Unexamined Publication (kokai) No. 207,462/1986 discloses a resin composition containing a polyarylene sulfide having an amino group or an amide group, a thermoplastic elastomer, and an inorganic filler, to be added as needed. This resin composition, however, suffers from the disadvantages that, although its impact strength can be improved to a practically available level by adding the thermoplastic elastomer in the amount of 30% by weight, it cannot be said that it satisfies requirements for impact strength to a sufficient extent and further its heat distortion temperature is largely reduced down to approximately 250.degree. C. and it becomes extremely poor in heat resistance.
On top of that, Japanese Patent Unexamined Publication (kokai) No. 51,944/1984 discloses a resin composition obtained by blending a polyphenylene sulfide with an epoxy resin; Japanese Patent Unexamined Publication (kokai) No. 51,945/1984 discloses a resin composition in which a polyphenylene sulfide is blended with a novolak-type epoxy resin; and Japanese Patent Unexamined Publication (kokai) No. 8,359/1985 discloses a resin composition resulting from a linear polyphenylene sulfide and an epoxy resin. These resin compositions, however, require comparatively large amounts of the epoxy resins to be added because the usual polyarylene sulfides have been used, and the effects of improvements in impact resistance and heat resistance cannot be said to be satisfactory.
Japanese Patent Unexamined Publication (kokai) No. 69,832/1985 discloses a thermoplastic resin composite material reinforced with fibers comprising 10% to 90% by weight of a polyphenylene sulfide, 90% to 10% by weight of a polyamide resin, and reinforced fibers having an average fiber length of 3 mm and longer.
Japanese Patent Unexamined Publication (kokai) No. 126,170/1986 discloses a polyamide resin composition comprising 50% to 5% by weight of a polyarylene sulfide and 95% to 50% by weight of nylon 46.
However, these resin compositions comprising simple blends have the problems that their mechanical strength may be reduced too much and the effect of improving impact strength may be less because of insufficient compatibility with each other.
Furthermore, Japanese Patent Unexamined Publication (kokai) No. 174,562/1989 discloses a polyphenylene sulfide resin composition comprising 1% to 99% by weight of a deionized polyphenylene sulfide and 1% to 99% by weight of a polyamide resin.
A further variant of polyphenylene sulfide resin compositions comprising a polyphenylene sulfide resin, a polyamide resin and an epoxy resin is disclosed in Japanese Patent Unexamined Publication (kokai) No. 146,939/1988.
These polyphenylene sulfide resin compositions have considerably improved properties by deionizing the polyphenylene or by adding the epoxy resin, in order to improve compatibility, however, the polyamide resin used has no reactivity with the polyphenylene sulfide resin so that stability may not be said to be satisfactory.